<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>原型链</title>
  </head>
  <body></body>
  <script>
    function Parent() {
      this.a = 1;
      this.b = [1, 2, this.a];
      this.c = { demo: 5 };
      this.show = function () {
        console.log(this.a, this.b, this.c.demo);
      };
    }
    function Child() {
      this.a = 2;
      this.change = function () {
        this.b.push(this.a);
        this.a = this.b.length;
        this.c.demo = this.a++;
      };
    }
    Child.prototype = new Parent();
    var parent = new Parent();
    var child1 = new Child();
    var child2 = new Child();
    child1.a = 11;
    child2.a = 12;
    parent.show(); // 1 [1, 2, 1] 5
    child1.show(); // 11 [1, 2, 1] 5
    child2.show(); // 12 [1, 2, 1] 5
    child1.change(); //
    child2.change(); //
    parent.show(); // 1 [1, 2, 1] 5
    child1.show(); // 5 [1, 2, 1, 11, 12] 5
    child2.show(); // 6 [1, 2, 1, 11, 12] 5
  </script>
</html>
